This invention relates to method and apparatus for forming a tread on a tire, and more particularly, to a method and apparatus wherein tread-forming shoes form a tread on rubber material.
In the formation of a tread on a tire, upper and lower mold portions are provided, each mold portion containing means defining a tread pattern. In one known embodiment, each mold portion contains a rigidly mounted solid ring, which defines the tread pattern, and in another known apparatus, each mold portion contains a resiliently mounted segmented ring (i.e., individual tread shoes). In both systems, it is common practice to initially completely close the two mold portions together, and then to apply fluid pressure to the tire to force the rubber into contact with the tread-forming shoes. The segmented ring design as described above is considered to have a certain advantage over the rigidly mounted solid ring system, since when the mold portions are moved apart to allow removal of the tire, the resiliently mounted shoes move radially outwardly some distance greater than the tread groove depth so that the tire can be removed from the apparatus without distorting the tread.
Since in such conventional systems the tire is inflated and expanded to force the rubber into the tread-forming means, the expansion and forces involved in forming the tread tend to displace radial and circumferential reinforcements from their ideal positions.
It will be understood that it would be considered advantageous for the tread to be formed on the tire with the tire structure remaining in its ideal position during the formation thereof through isolation of the forces of the reinforcement of the tire.
It will also be understood that, while achieving proper formation of the tread, the method thereof, and the apparatus for achieving such method, should, with advantage, be extremely simple and efficient.